Baffle Height Research Articles

Vertical baffles in a fluidized bed reactor: Hydraulic assessment with a numerical and experimental approach

The hydrodynamics of a mini fluidizedbedreactor with and without vertical baffles has been studied with Computational Fluid Dynamics (CFD) and verified experimentally for several selected configurations. The CFD – Lagrangian Multiphase Method (CFD-LMM) approach was adopted. The gas was fed at a flow rate of 18Lmin−1 via twelve tangential inlets, creating a vortex flow around a cone in the downstream section, and additionally via a single vertical inlet (2Lmin−1) in the top plane of the cone. Relevant parameters on the friction factor, namely baffle height, inclination angle, arrangement of the baffles and the distance between the two baffle sets, have been studied. The results showed that increasing the number of baffles, the particle non-uniformity parameter decreases from 75 to 40 %. Moreover, the aligned arrangement was superior to staggered one by providing more fluid mixing. Finally, the trapezoidal baffles further improved the bed uniformity, allowing a decrease of the experimental particle non-uniformity index by more than four times as compared to the reactor without baffles tested in the same conditions.

Effect analysis on the low-temperature preheating performance of a novel micro-combustor air preheater for the cold start of the Li-ion battery packs

In this work, a micro-combustor (MC) air preheater as the heat source is developed. This novel air preheater has a compact size and outputs hot air with a wide range of temperatures with high temperature uniformity, which can well meet the preheating needs of Li-ion batteries in cold environments. Numerical studies are carried out to investigate the effects of baffle height, number of fins Nfin, hot air inlet velocity, cold air inlet velocity and combustor inlet velocity on the performance of the air preheater. The heating power of the air preheater can be adjusted by changing combustor inlet velocity Vcombustor, the outlet temperature can be easily adjusted by changing cold air inlet velocity Vcold and hot air inlet velocity Vhot, and the addition of baffles makes the outlet temperature very uniform. The results show that the height of the baffle of 20 mm and 30 mm makes ΔTair not exceed 1.5 K. The air preheater performance is better with fin number 6, and the maximum air temperature of 309.8 K is obtained with fin number and Vhot of 6 and 0.3 m/s respectively. Tair can vary between 287.8 K and 309.8 K when Vcombustor=12 m/s.

Influence of straight and inclined baffles on enhancement of battery thermal management system performance

Battery thermal management systems (BTMSs) are used in electric vehicles (EVs) to regulate the heat generated by batteries while in use. Existing research on the improvement of BTMSs revealed that more research can be done by exploring different strategies to extend the service life and capabilities of EV batteries beyond the current limitations. In this study, effects of orientation of baffles; straight (90°), inclined (60° and 30°), height of baffles, thickness of baffles, positioning of baffles and number of baffles on the performance of conventional Z – Type BTMS were studied using Computational Fluid Dynamics (CFD) approach. The CFD approach was validated with existing experimental result from literature. Findings from the study showed that for straight baffle, the maximum temperature (Tmax) reduces as the height of baffles decreases. Furthermore, increasing the baffle thickness from 1 mm to 2 mm, produced reduction in Tmax by 0.26 K. For inclined baffles, by comparing the BTMS without baffles and BTMS with 2 baffles, Tmax and maximum temperature difference (ΔTmax) reduced by 0.82 K and 0.68 K, respectively at angle 60°, and reduced by 1.65 K and 1.43 K, respectively at angle 30°. The BTMS with 2 baffles, inclined at angle 60°, with height of 6 mm and thickness of 1 mm, yielded the optimum Tmax (Lowest) value of 333.15 K, a reduction by 2.65 K when compared to the conventional Z – Type BTMS. This was also accompanied with a slight increase in ΔP by 1.12 Pa. In conclusion, it can be said that findings from this study will be beneficial in enhancing the design of BTMSs through adequate selection and utilization of baffles orientation.

Thermal effectiveness analysis of heat exchange tube with staggered louver-punched V-baffles

An experiment has been conducted to ascertain the optimal approach for enhancing the convective transmission of heat in a heat exchanger tube by periodically positioning staggered louver-punched V-baffle (SLVB) vortex generators on a perforated tape. The louver-punched V-baffles were staggered and set up with two patterns: V-apex directing upstream (VU) and downstream (VD), and each featured a louver-punched aperture to minimize friction loss. The aim of this work was to rise the thermal effectiveness as well as the Nusselt number ratio (NuR) at optimal effectiveness in order to cut down on overall dimension of heat exchangers. Consequently, the research findings focused on behaviors of heat transmission and frictional loss, incorporating generated entropy, through a variety of Reynolds numbers (Re) spanning 29,270 to 4762. The SLVB elements were designed and placed in VU and VD forms using three relative pitches (PR = 0.5, 1.0, and 1.5) as well as six louver-flapped angles (θ = 0°, 10°, 20°, 30°, 45°, and 90°), all at the same attack angle (α = 52°), a baffle height ratio (BR = 0.3) and a louver size ratio (LR = 0.73). As demonstrated by the experiment, the θ = 20° generated the best heat transfer of all PR values, up to 6.55 times greater than the smooth tube, despite having a lower friction loss than the θ = 0° (solid baffle). At PR = 0.5, θ = 20° and smaller Re, the optimum thermal effectiveness factor (TEF) and NuR values were, respectively, about 2.65 and 6.55 for the VU SLVB and 2.52 and 6.04 for the VD one. It implied that the TEF strategies can be utilized to anticipate the best effectiveness under identical scenarios. Also, correlations for the critical parameters, namely, Nu, f, and TEF, were estimated and documented.

Study on the influence of baffle height and angle on the performance of coarse powder separator in power plant based on CFD-DPM method

In this study, the two-phase motion characteristics in a coarse powder separator were investigated using computational fluid dynamics (CFD) method, discrete particle model (DPM) and isokinetic sampling experimental method, and the structure of the coarse powder separator was optimized to improve the efficiency of the separator. The results showed that the particle separation in different separation zones was also dominated by gravity separation and centrifugal separation, respectively. When the baffle angle was increased from 20° to 60° at a low mounting height, the tangential velocity in the separation zone was reduced by 67 % and the axial velocity was increased by 33 %. The effects of the baffle angle on the tangential and axial velocities were weakened with the rise of the baffles mounting height. The optimum operating condition of the chosen powder separator involved a baffle angle α 30°, a baffle height H = 6.27 m, and a inlet velocity v = 19.3 m/s. The fineness of coal powder at the fine powder outlet was reduced by 60 % and the fineness of coal powder at the coarse powder return port was improved by 43 % for the optimized model compared with the original coarse powder separator.

Investigation of the Deformation Behavior of Baffle Structures Impacted by Debris Flow Based on Physical Modelling

The utilization of baffle structures as a highly effective strategy for mitigating debris flow has attracted significant scholarly attention in recent years. Although the predominant focus of existing research has been on augmenting the energy dissipation capabilities of baffle structures, their deformation behavior under impact load has not been extensively investigated. Addressing this research gap, the current study systematically designs a series of physical model experiments, incorporating variables such as baffle height, shape, and various combinations of baffle types to comprehensively analyze the deformation characteristics of baffles subjected to debris flow impact. The experimental results reveal that the deformation of baffle group structures demonstrates a marked non-uniform spatial distribution and exhibits a latency effect. Additionally, distinct baffle configurations show considerable variations in peak strain, suggesting that combining different baffle shapes can not only optimize energy dissipation but also enhance resistance to deformation. Moreover, the relationship between baffle height and the development of deformation in relation to energy dissipation capacity is inconsistent, indicating that deformation must be a key consideration in the design of baffle structures. Consequently, this paper advocates for the formulation of a deformation-based design strategy for baffle structures, with the findings presented herein providing a foundational reference for future studies.

Equivalent analytical model for liquid sloshing in a 2-D rectangular container with multiple vertical baffles by subdomain partition approach

An equivalent analytical model of sloshing in a two-dimensional (2-D) rigid rectangular container equipped with multiple vertical baffles is presented. Firstly, according to the subdomain partition approach, the total liquid domain is partitioned into subdomains with the pure interface and boundary conditions. The separation of variables is utilized to achieve the velocity potential for subdomains. Then, sloshing characteristics are solved according to continuity and free surface conditions. According to the mode orthogonality of sloshing, the governing motion equation for sloshing under horizontal excitation is given by introducing generalized time coordinates. Besides, by producing the same hydrodynamic shear and overturning moment as those from the original container-liquid-baffle system, a mass-spring analytical model of the continuous liquid sloshing is established. The equivalent masses and corresponding locations are presented in the model. The feasibility of the present approach is verified by conducting comparative investigations. Finally, by utilizing normalized equivalent model parameters, the sloshing behaviors of the baffled container are investigated regarding baffle positions and heights as well as the liquid height, respectively.

Influence of baffle height on the in-cylinder mixing and performance characteristics of a gasoline direct injection engine - a CFD investigation

In modern GDI engines, in-cylinder flows play a crucial role in the performance and emission characteristics. Adding baffles to the cylinder head is one way to enhance these flows, as baffle effectiveness is linked to its height. This study aims to investigate the influence of baffle height on the in-cylinder flows and its impact on the performance and emission characteristics of a four-stroke, four-valve, spray-guided GDI engine using computational fluid dynamics (CFD) analysis. The maximum baffle height is determined based on the geometry of the engine. Throughout the analysis, the engine operates at a constant speed of 1000 rev/min., under part-load conditions. From the results, the baffle heights of 2 mm and 3 mm significantly improve mixture stratification compared to the base engine. Furthermore, the indicated mean effective pressure (IMEP) for the engine with 2 mm and 3 mm baffle height improves by about 3% and 4%, respectively, compared to the base engine. In addition, with the increase in the baffle height, there is a significant reduction in the HC emissions with a marginal increase in NOX emissions.

EXPLORING THE IMPACT OF GEOMETRIC PARAMETERS ON HEAT TRANSFER AND FLUID FLOW CHARACTERISTICS IN CROSS-TRIANGULAR GROOVED CHANNELS: A COMPUTATIONAL STUDY

In this study, the impact of geometric parameters of rectangular baffles with varying location angles and heights is investigated on the heat transfer and fluid flow characteristics of cross-triangular grooved channels. Computational methods are employed to explore these effects, utilizing the Ansys-Fluent program to solve the Navier-Stokes and energy equations, incorporating the k-ε turbulence model for numerical simulations. The inlet temperature of the air, serving as the working fluid, is set at 293 K, while the wall surface temperature of the lower triangular grooved channel remains fixed at 373 K. Rectangular baffles are tested with angles of 30°, 60°, and 90°, and heights of 0.25H, 0.5H, and 0.75H, respectively. The numerical results show good agreement with a 3.53% deviation compared to existing empirical data in the literature. The obtained findings are presented in terms of mean Nusselt (Num) number, fluid temperature, and Performance Evaluation Criterion (PEC) number variations taking into consideration of pressure drop for each rectangular baffle angle and height. Additionally, contour distributions of temperature and velocity are evaluated for different Reynolds numbers (Re) and arrangements of rectangular baffles. It has been determined that the Nu number value increases by 197.56% at a 90° angle and 0.75H height, compared to the 0.25H baffle height at Re=6000. Furthermore, at Re=1000, the PEC number is 84.50% higher with a baffle height of 0.25H and a baffle angle of 30° compared to the condition with a 90° angle.

Thermal effectiveness enhancement in heat exchange tube using louver-punched V-baffles

An efficient technique for reducing frictional loss by punching holes on the surface of vortex generators has been extensively researched, particularly in the form of louver-punched holes. This article describes an experimental and numerical examination of thermal effectiveness in a heat exchange tube with louvered baffle vortex generators (LBVG). As air was directed to the LBVG-inserted tube with a consistent heat flux, the flow was measured in a turbulent regime. The LBVGs were set at 30° attack angle (α) and mounted at regular intervals on a two-sided flat tape with one relative baffle height (b/D = RB = 0.25) and pitch (P/D= RP = 1) at the first step. The baffles had five different louver angles (θ = 0 ˗ 90°) and three different relative louver sizes (LR= e/b = 0.4, 0.56, and 0.72). The Nusselt number ratio (NuR), friction factor ratio (fR), and thermal effectiveness factor (TEF) were utilized to quantify the performance of LBVGs. The findings showed that LBVGs had much lower fR values than solid baffles (without holes), whereas NuR values decreased slightly. When θ and LR were reduced, the fR and NuR for LBVGs increased until they resembled those for solid baffles. Through numerical simulations using the realizable k-ε turbulent model based on the finite volume method, the flow and temperature fields of various cases were generated; their results were verified via analysis of the fluid flow patterns. The computational findings revealed that the jet flow from the louver hole could boost heat transfer, and TEF of LBVGs varied depending on the placement of the hole. According to the computations, the optimal TEF at RP = 0.75, LR = 0.4, and θ1 = 20° is roughly 2.64, and the hole should be placed toward the baffle ends rather than in the middle.

Heat transfer and thermal–hydraulic evaluations of cross-circular grooved rectangular flow ducts depending on rectangular baffle design parameters

The cross-grooved rectangular flow ducts are largely used for plate heat exchangers. In this work, so as to better the heat transfer in cross-grooved rectangular ducts with circular grooves, rectangular baffles were located in the flow duct, and the influences of the rectangular baffle angles and heights on the features of heat transfer were numerically performed in detail. Equations of Navier–Stokes and energy were resolved by employing a program of Ansys-Fluent with k–ε turbulence model as steady and three-dimensional. Air employed as working fluid has a temperature of inlet 293 K while the circular groove’s wall temperature is 373 K. Rectangular baffles have various angles of 30°, 60°, and 90°, and heights of 0.25 H, 0.5 H, and 0.75 H. The mean Nusselt number (Num), temperature, turbulence kinetic energy (TKE), pressure, and PEC (Performance Evaluation Criterion) number of the flow duct with rectangular baffles were evaluated by comparing it with the cross-circular grooved channel non-baffle. Besides, the contours of velocity, turbulence kinetic energy, temperature, and velocity vector were exhibited for the cross-circular grooved rectangular channels with different baffle angles and height arrangements. Results were matched with experimental and numerical outcomes of the study found in the literature, and it was observed that they were fairly coherent. For Re = 6000, the number of Num increases by 180.48% in the duct with a 90° angle and 0.75 H baffle height compared to the duct non-baffle, and for 30° baffle angle, the PEC value at 0.25 H baffle height is 66.88% higher than that in the 0.5 H.Graphical Compared to the temperature contour distribution in the non-baffle state, the temperature gradient increases due to the turbulence intensity created by the inserting of baffles to the circular grooved ducts. When the baffle height is increased to 0.75 H, the increase in fluid temperatures toward the end of the ducts is the clearest evidence of this situation. Thus, while cooling increases in circular grooves, the temperature gradient in the duct above the circular grooved section gets better, especially in the case of 0.75 H height and 90° baffle angle. Temperature distribution contours of the ducts for non-baffle and with baffle of 90° angle and 0.75 H height for Re = 6000.

An efficient framework for controllable micromixer design through the fusion of data-driven modeling and machine learning insights: Numerical and experimental analysis

Micromixers are inevitable components in microfluidics, micro-electro-mechanical devices, and numerous bio-chemical assays. By assays, we mean diverse analytical procedures encompassing gene engineering, the manipulation of genetic material; nanoparticle synthesis, focusing on the controlled creation of nanoparticles; and cell lysis, involving cell membranes disruption for the release of intracellular substances for diagnostic purposes. In these assays, the homogeneous mixture of two or more fluids is crucial. However, designing an efficient micromixer providing high homogeneity and low pressure drop, while maintaining controllability, is challenging. Controllability refers to the design of a micro-system tailored to meet the specific requirements of a given assay. This study proposes a controllable framework, combining machine learning and statistical modeling. The framework begins with the generation of a reference parametric micro-structure, herein a microchannel with L-shaped baffles and featuring seven variables. A response surface method, a data-driven modeling scheme, is used to establish functional relationships between design variables and objective functions. The study reveals that the baffle height significantly impacts the system functionality, increasing the mixing index by over 40% and the pressure drop by more than 220% when reaching its upper limit. Dean-like secondary vortexes are generated in the microchannel at Re = 10, demonstrating the efficiency of the implemented baffles. Subsequently, multi-objective optimization methods, non-dominated sorting genetic algorithm (NSGA-II) and differential evolution (DE), are employed, with adaptable variable constraints. Comparative analysis of the methods shows that DE finds superior optimum solutions in fewer iterations. Finally, an optimum structure is fabricated using soft lithography, and experimental tests are conducted for validation.

RESEARCH OF TRIANGULAR BAFFLE PLACEMENT EFFECT ON THE HEAT TRANSFER AND FLOW FEATURES IN CROSS-CIRCULAR GROOVED TRIANGULAR CHANNELS

In this study, heat transfer performance and fluid flow properties for cross-circular grooved triangular ducts having different location angles and heights of the triangular baffles are studied numerically. The ANSYS Fluent program is applied to solve the equations of energy and the Navier-Stokes equations by employing the <i>k</i>-ε turbulence model in computational calculations. While the inlet temperature of the working fluid (air) is 293 K, the surface temperature of the lower circular grooved channels is taken constant at 373 K. Triangular baffles have different angles of 30°, 60°, and 90° and heights of 0.25H, 0.5H, and 0.75H. The range of the Reynolds number (Re) employed in this study is 1000-6000. Numerical results agreed with a 3.53% deviation according to empirical work that existed in the literature. The attained outcomes are presented as mean Nusselt number (Nu<sub>m</sub>), fluid temperature, turbulence kinetic energy, pressure, and performance evaluation criterion (PEC) variations for each triangular baffle angle and height. Contour distributions of the temperature, velocity, turbulence kinetic energy, and velocity vector are also evaluated for distinct Re numbers and triangular baffle arrangements. For Re = 3000, the Nu<sub>m</sub> number in the channel with a 90° baffle angle and 0.75H baffle height is 136.73% higher than that in the channel with 0.25H baffle height. In the channel with 0.25H baffle height, the PEC value is 91.91% higher in the 30° baffle angle condition than in the 90° one.

Baffle structure effects on mass transfer and pressure drop of HT-PEMFC with orientated flow channels

Flow field design is critical to improving the overall performance of high-temperature proton exchange membrane fuel cells. Adding baffles in the flow channel has been proven to be effective in enhancing mass transfer. In this study, fuel cells with different baffle numbers, heights, and arrangements are numerically simulated to investigate the effects of reactant velocity, concentration distribution, and pressure drop on mass transfer and output performance. The results show that baffles are beneficial in improving cell performance, especially under high current density. With the increase in baffle number and height, the concentration of the reactant at the outlet decreases and the output power increases with the increase in pressure drop. The net power density growth rate is defined to characterize the cell performance. A lower pressure drop reduces the pumping power loss generated during reactant transfer, resulting in a staggered baffle structure with the highest net power density of 4329.65 W/m2. Compared with the traditional and parallel baffle channels, this value is improved by about 11.74% and 4.83%, respectively. Therefore, the optimized baffle channel can enhance the mass transfer, reduce the pumping power, and further improve the cell performance, providing an effective guide for the optimal design and development direction of the orientated flow channel.

Thermo-hydraulic performance investigation of double pass solar air heater integrated with PCM-based thermal energy storage

The solar air heater (SAH) is one of the ways to utilize solar energy for the purpose of drying, greenhouse heating and air conditioning. However, the SAHs are unable to deliver reliable thermo-hydraulic performance as a result of the intermittent nature of solar energy and the low convective heat transfer coefficient. Thus, in the present study, a three-dimensional numerical investigation is performed to study the thermo-hydraulic performance of the double pass solar air heater (DPSAH) having semi-cylindrical PCM tubes and perforated baffles as roughness geometry. The parameters selected for this study include baffle height ratio (eb/H) from 0.4 and 0.8, tube radius ratio (rt/H) from 0.2 and 0.5, and Reynolds numbers (Re) from 3000 and 13,000. Experimental validation has been conducted to verify the numerical results, and it has been found to be well-validated with mean absolute errors of 6.5 % and 1.2 % for the Nusselt number (Nur) and friction factor (fr), respectively. The maximum Nusselt number (Nur) is found to be 200.08 at Re of 13,000, while the maximum friction factor (fr) is measured to be 0.6290 at Re of 3000, which corresponds to eb/H of 0.8 and rt/H of 0.3. The maximum heat transfer enhancement (Nur/Nus) in comparison to the smooth duct is found to be 5.08 times with a maximum friction factor increment (fr/fs) of 65.80 times, which corresponds to eb/H of 0.8, Re of 13,000 and rt/H of 0.3. The maximum thermo-hydraulic performance parameter (THPP) is observed to be 1.83 at Re of 13,000, rt/H of 0.2 and eb/H of 0.4. This study contributes to the design and optimisation of SAHs by incorporating thermal energy storage and roughness geometries.

An Experimental Study of Pool Fire Characteristics under the Effects of Cross Winds and Baffles

The pool fires that occur behind obstructions in a ventilated environment are very different from other wind-blown pool fires. The pool fire formed by fuel leakage in an engine nacelle is a typical example of a pool fire influenced by cross winds and baffles. Mastering the combustion characteristics of this type of fire is of great significance for fire prevention and control. In this study, the burning rate, flame length, and flame tilt angle of heptane pool fires behind a baffle under different cross wind velocities (ranging from 0 to 5 m/s) were experimentally investigated. Square pool fires with dimension of 8 cm and 12 cm with baffle height from 4 to 12 cm and different distances between fire and baffle (0, 20, 30 cm) were tested in a wind tunnel. The experimental results show that the burning rate increases with the increase in cross wind velocity for each baffle height. As wind velocity exceeds 2 m/s, the burning rate first decreases and then increases with the increase in baffle height. The flame length initially increases and then decreases with increasing wind velocity. The upper flame tilt angle is mainly affected by the cross wind, while the bottom flame tilt angle is influenced by the combined effects of cross wind velocity, baffle height, and distance between baffle and flame. The empirical correlations under different distances between baffle and flame, with wind velocity and baffle height accounted for, are then proposed for the dimensionless heat release rate and the flame length of heptane pool fires.

Numerical study on the effect of baffle structure on the heat transfer performance of elastic tube bundle heat exchanger

To make up for the research gaps in the existing literature on the effect of baffle structural parameters on the vibration and heat transfer of elastic tube bundle (ETB) heat exchangers, and improve the comprehensive heat transfer performance (HTP) of heat exchangers, based on an improved elastic tube bundle (I-ETB) heat exchanger used in previous studies, using the bi-directional fluid-structure interaction calculation method, the effects of the baffle structure improvement (height and curvature) on the comprehensive HTP of the I-ETB heat exchanger at different inlet velocities (Uin) were numerically studied. The results show that: while the height factor increases from 0.70 to 0.80, the vibration amplitude of I-ETBs decreases maximum by 10.05 %, and the heat transfer coefficient (h) of I-ETB increases maximum by 5.50 %. Increasing the baffle height improves the comprehensive HTP while suppressing the vibration of the I-ETBs. While the baffle curvature is 10°, the vibration of I-ETBs is the most intense, with the amplitude of the I-ETBs improving maximum by 10.79 %. The Nusselt number per unit pressure drop Nu/ΔP and performance evaluation criteria PEC and JF (a dimensionless number related to Colburn factor j and Fanning friction factor f) values of the heat exchanger all reach the maximum while the baffle curvature is 10°. The increase of baffle curvature has a positive effect on the vibration-enhanced HTP of the I-ETBs, and when the curvature is 10°, the comprehensive HTP of the heat exchanger is better.

Channel structure design and optimization for immersion cooling system of lithium-ion batteries

The phenomenon of heat accumulation during the discharge process of lithium-ion batteries (LIBs) significantly impacts their performance, lifespan, and safety. A well-designed cooling architecture is a critical issue for solving the heat accumulation problem of the battery immersion cooling system (BICS). In this study, four cooling channel design schemes (CC-1, CC-2, CC-3, and CC-4) for the BICS were developed. The effect of various cooling channel structures on the cooling performance of BICS has been studied. Comparative analysis reveals that the CC-1 structure demonstrates the most outstanding overall performance. It effectively manages battery pack temperatures while maintaining temperature uniformity, and its pressure drop remains comparable to other designs. Applying orthogonal analysis, the CC-1 structure was further optimized. Subsequently, a linear weighting method was employed to analyze multiple evaluation indexes comprehensively. The following optimal structural parameters were obtained: battery spacing (S) of 4 mm, baffle height (H) of 42 mm, distance from the inlet to the channel bottom (L) of 14 mm, and a coolant mass flow rate (Q) of 0.04 kg/s. Compared to before optimization, the battery pack's maximum temperature and temperature difference have been diminished by 17.9 % and 20.8 %.

The effects of rectangular baffle angles and heights on heat transfer and pressure drop performance in cross-triangular grooved rectangular flow ducts

The improvements in heat exchangers mainly focus on rising energy efficiency. The cross-grooved rectangular flow ducts are largely used for plate heat exchangers. In this study, to enhance the heat transfer and hydraulic-thermal performance in the cross-grooved rectangular ducts with triangular grooves, rectangular baffles were located in the duct, and the influences of the rectangular baffle angles and heights on the features of the heat transfer and pressure drop were numerically analyzed in detail. The equations of Navier-Stokes and energy were solved by employing the Ansys-Fluent program with the k-ε turbulence model as steady and three-dimensional. Air used as working fluid has an inlet temperature of 293 K while the triangular groove’s wall temperature is 373 K. Rectangular baffles have various angles of 30°, 60°, and 90°, and heights of 0.25H, 0.5H, and 0.75H. The mean Nusselt number (Num), dimensionless temperature (T*), turbulence kinetic energy (TKE*), pressure (p*), and performance evaluation criterion (PEC) number of the ducts with rectangular baffles were evaluated by comparing with the cross-triangular grooved duct without baffle. Also, the contours of turbulence kinetic energy, temperature, and velocity vector were exhibited for the cross-triangular grooved rectangular ducts with different arrangements of baffle angles and heights. Results were matched with experimental and computational outcomes of the study found in the literature, and it was observed that they were fairly compatible. The increment rate of Num at 90° baffle angle and 0.75H height is 197.56 % higher for Re = 6000 compared to 0.25H. Besides, for Re = 1000, the PEC number is 84.50 % higher at 0.25H baffle height and 30° angle than at 90°.

Design and simulation of anti-sloshing baffles applied to detumbling payload propellant tanks

The method to suppress the liquid sloshing in the tank applied to the jet detumbling payload is investigated in this study. Among all kinds of anti-sloshing structures, the symmetrical annular baffle was chosen due to the features of impact on the payload’s tank. The damped mass-spring liquid sloshing model established is used to compare the damping ratio of the baffle with different baffle layers and different baffle heights. Using FLUENT software, based on VOF (volume of fluid) numerical simulation technology, the damping effect of baffles with different layers and heights is simulated. The results show that 3-layer 15mm or 4-layer 10mm baffles can effectively reduce the influence of liquid sloshing. The damping ratio of the storage tank with a 3-layer 15mm anti-sloshing baffle is at least 18.3 times that of a smooth tank, and the damping ratio of the tank with a 4-layer 10mm anti-sloshing baffle is at least 18.7 times that of a smooth tank.